2-2-11 What is the difference between weathering and erosion?

1. 2-2-11What is the difference between weathering and erosion? Do Now: Answer the aim question. HW: R&H pp. 182-185, A&E #1-10

2. Weathering- the breakdown of rock at the earth’s surface into sediments (clay, silt, sand, pebbles, cobbles, boulders • Types of Weathering: • 1. Physical – rock is physically broken into smaller sediments. • 2. Chemical- rock is chemically changed by reacting with different elements and weakening the rock by changing its color, texture, and chemical composition.

3. Factors that affect the rate of weathering. • 1. Exposure- rocks that are exposed to air, water, and animals will weather faster. • 2. Particle size- smaller particles have greater surface area exposed to weathering making them break down at a faster rate. • 3. Mineral composition- harder minerals weather slower than softer minerals. • 4. Climate- Hot and humid climates favor chemical weathering and less humid with varying temperatures above and below freezing favor physical weathering. • ** You can have physical weathering without having chemical weathering but you can’t have chemical weathering without also having physical weathering.

4. Soil Formation- soil is made from weathered rock and biologic activity • Rock is broken down by physical weathering and then biologic activity will chemically change the rock and add nutrients to create soil. • Over time a very immature soil will become mature by developing rich soil horizons.

5. Steps to soil formation

6. 2-3-11Aim: How is soil formed? • Do Now: • 1. What is the difference between chemical and physical weathering? • 2. If rocks are just physically weathered for a long period of time what will they turn in to? • 3. What is the underlying force to all agents of erosion? • HW: Work on books

7. 2-8-11Aim: What is the life cycle of a stream? • Do Now: • 1. List the 5 agents of erosion. • 2.Which agent of erosion can carry the largest sediment and why? • 2. Which agent of erosion can carry the smallest sediment and why? • HW- R&H pp.187-194, A&E #11-29

8. 2-9-11How do wind and glaciers erode? • Do Now: • 1. What is soil made up of? • 2. List the things that would increase the velocity of a river. • 3. Why does the wind not erode things at higher levels? • 4. On what side of a meander does erosion occur and why? • 5. If a stream slows from 100 cm/s to 1 cm/s what particles would drop out? Use RT p.6 • HW: Finish lab, Study Topic 9 for quiz Friday.

9. 2-10-11What happens to sediments during erosion? • Do Now: • 1. What is the difference between a river valley and a glacial valley? • 2. As a stream matures, what happens to slope, velocity, carrying power, load, erosion and deposition? HW: Study for Topic 9 quiz.

10. How does a stream carry it’s sediment. • A stream’s ability to carry sediment is based on its velocity. This is called carrying power. • The amount of sediment a stream is carrying is called the stream load. • Floatation- particles can float on top of a stream(move slower than stream). • Suspension-particles carried within a stream(move slower than stream). • Solution- particles dissolved in a stream (move at the same speed as the stream). • Bouncing and rolling- particles move along the stream bed and move slower than the stream.

11. What does erosion do to sediments? • Erosion will make sediments smaller and will change their appearance • 1. Running water will round and smooth particles. • 2. Wind will frost and pit particles as well as round them. • 3. Gravity will break particles leaving them sharp and angular. • Glaciers will sub round particles leaving parallel grooves, striations(parallel scratches), and polishing particles.